Today, in New York City, just blocks from where World Trade towers stood, a jury convicted Osama bin Laden's son-in-law of conspiring to kill Americans. Sulaiman Abu Ghaith was a chief propagandist for al-Qaida. He was seen in videos with bin Laden immediately after the 9/11 attacks. Now he faces life in prison when he's sentenced later this year.

NPR Justice Department correspondent Carrie Johnson has been following the case, and she joins me now. And, Carrie, first, help us understand what role did this man play in the operations after the 9/11 attack.

CARRIE JOHNSON, BYLINE: Well, the FBI compared him to something like a propaganda minister in a developing country, or a consigliere in a mob family. In essence, they believe he was a confidante of Osama bin Laden, who seemed to single him out because he was smart. And, of course, you may know about him because he appeared in a video alongside bin Laden just shortly after 9/11 where he warned that, quote, "a great army is gathering against the United States."

For months after those attacks, Audie, Abu Ghaith got talking points from bin Laden and senior leaders of al-Qaida. But prosecutors say he went beyond just talk by getting others in training camps to swear an oath of loyalty to al-Qaida and to vow to kill Americans.

CORNISH: But looking in those days after 9/11, I mean, why did it take so long to bring him to justice?

JOHNSON: The short answer is he went on the run. He got smuggled out of Afghanistan and into Iran in 2002, and he hid out there for a really long time until authorities nabbed him in Jordan last year and sent him to New York for trial.

CORNISH: Now give us some details about that trial, key moments.

JOHNSON: So the biggest shocker, Audie, was that Abu Ghaith took the witness stand, which came out of leftfield for a lot of people who watched these trials. Abu Ghaith acknowledged that he knew something big was happening around 9/11, but says he didn't know that 3,000 Americans would die that day. He also told the jury in sometimes riveting testimony about going to a cave near Kabul where bin Laden was hiding out the same night of 9/11.

And he really went hard to argue himself out of those video images of Abu Ghaith sitting next to bin Laden the day after those 9/11 attacks. But the defense tried to argue that he didn't play a major role in the al-Qaida operation. He was motivated by religion, not a desire to kill Americans. The jury didn't buy it. It took less than a day to convict him on all counts.

CORNISH: You know, Carrie, there's been such a political debate about whether criminal courts are even the right place to prosecute terrorists. What's been the reaction to this verdict?

JOHNSON: Well, it didn't clog up traffic in Lower Manhattan or present any major security challenges, which, of course, were reasons cited for not trying 9/11 masterminds like Khalid Sheikh Mohammed in New York years ago. The top prosecutor in New York, Preet Bharara, cited what was the ordinary nature of the Abu Ghaith case, that Abu Ghaith got his arguments heard in a trial that lasted about a month. And a unanimous jury of U.S. persons ultimately convicted him, Audie, without much fuss, which is really unlike the alternative, the Guantanamo prison trials, where 9/11 plotters like Khalid Sheikh Mohammed are, still nowhere near a trial date all these years later.

And Attorney General Eric Holder says that he hopes this Abu Ghaith verdict finally puts to rest all these political arguments about using New York Courts for national security cases in the future.